Normal-mode analysis for collective neutrino oscillations
Normal-mode analysis for collective neutrino oscillations
复制标题
集体中微子振荡的简正模分析
DOI：
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发表时间：
2018
影响因子：
6.4
通讯作者：
Tobias Stirner
中科院分区：
文献类型：
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作者：
Sagar Airen;F. Capozzi;S. Chakraborty;B. Dasgupta;G. Raffelt;Tobias Stirner
在相互作用的中微子气体中，出现了可传播或不稳定的风味相干集体模式。我们导出了线性体系中与中微子能量和角度分布有关的一般色散关系。基本尺度为真空振荡频率ω=Δ m2/(2E)，中微子-中微子相互作用能μ=√2GF；nν，物质势λ=√2GF ne。集体模需要不消失的μ，即使ω=0（“快模”）也可能是动态的，或者它们可能需要ω=0（“慢模”）。不稳定快模的生长速率本身可以是快的（与ω无关），也可以是慢的（被√|ω/μ|抑制）。我们澄清了风味混合的作用，这在集体模式的识别中被忽视，但对于触发集体风味运动是必要的。需要一个大的物质效应来提供风味演化的近似固定点，而需要物质和/或中微子的空间或时间变化作为触发器，即将质量项提供的干扰转化为种子稳定或不稳定的风味波。我们举出明确的例子来说明这些观点。
In an interacting neutrino gas, collective modes of flavor coherence emerge that can be propagating or unstable. We derive the general dispersion relation in the linear regime that depends on the neutrino energy and angle distribution. The essential scales are the vacuum oscillation frequency ω=Δ m2/(2E), the neutrino-neutrino interaction energy μ=√2GF; nν, and the matter potential λ=√2GF ne. Collective modes require non-vanishing μ and may be dynamical even for ω=0 (“fast modes”), or they may require ω¬=0 (“slow modes”). The growth rate of unstable fast modes can be fast itself (independent of ω) or can be slow (suppressed by √|ω/μ|). We clarify the role of flavor mixing, which is ignored for the identification of collective modes, but necessary to trigger collective flavor motion. A large matter effect is needed to provide an approximate fixed point of flavor evolution, while spatial or temporal variations of matter and/or neutrinos are required as a trigger, i.e., to translate the disturbance provided by the mass term to seed stable or unstable flavor waves. We work out explicit examples to illustrate these points.